[Issue]: Chunks outside the camera frustum get culled too aggressively.

[Norsyd]

Description

Beddium Version: 1.2.4-j8
Forge/MC: 1.7.10 Forge
FalseTweaks: 4.4.0
GPU/Driver: Intel(R) Arc(TM) Graphics

Description

Chunks outside the camera frustum get culled too aggressively. When
the camera rotates quickly, edge chunks visibly pop in / flicker for
1-2 frames at the screen border before becoming fully rendered.

Reproduction

1. Stand in any open area with render distance ≥ 12
2. Whip the camera left/right quickly
3. Observe chunks appearing at the screen edge with a 1-frame delay

Tested

• All terrain config combinations had NO effect:
  • FastFog on/off
  • FastFogAsm on/off
  • ChunkDrawMode Vanilla / Fast (with FastChunkDrawModeFogBias=-16)
  • UseMultiDrawIndirect on/off
  • LockTessellatorMode on/off
  • MEGAChunks 0
• Setting B:TerrainRendering=false fully eliminates the issue,
  confirming it originates in Celeritas-based chunk culling.

Suspected

Frustum is sampled once per visibility pass; with fast rotation,
chunks that just entered the frustum are not queued before the next
frame draws. Possibly missing a frustum-expansion margin or
double-buffered visibility set.

Attachments

• Video: QQ20260511-163941-HD.mp4
• fml-client-latest.log

fml_client_latest.log, and crash reports, if any.

fml-client-latest.log
QQ20260511-163941-HD.mp4

I have submitted the required files

• I confirm that i have attached the required log files as a github attachment, and not as a pastebin/mclogs link.

[Norsyd]

Status: Fixed (local bytecode patch on the shadowed Celeritas class inside the JAR)
Beddium Version: 1.2.4-j8 (unchanged from original report)
Patched file: org/embeddedt/embeddium/impl/render/viewport/frustum/SimpleFrustum.class
Padding value: 32.0F (2 chunks) — tunable
Origin: This lives in Celeritas (org.embeddedt.celeritas:celeritas-common:2.4.0-dev.3), not in Beddium-specific code. The fix should ideally land upstream.

Root cause

SimpleFrustum.testAab(...) forwards the section AABB directly to JOML's FrustumIntersection.testAab with no safety margin. The occlusion culler in OcclusionCuller samples the frustum once per visibility pass; under fast camera rotation, sections that have just entered the frustum miss the cutoff for the current frame and only get queued one tick later, producing the 1–2 frame pop-in at the screen edge.

Fix

Expand the queried AABB by FRUSTUM_PAD blocks on every axis before delegating to JOML. Performance stays close to original (far-out sections are still culled) but sections within ~2 chunks of the frustum edge are always considered visible.

Before:

public boolean testAab(float minX, float minY, float minZ,
                       float maxX, float maxY, float maxZ) {
    return this.frustum.testAab(minX, minY, minZ, maxX, maxY, maxZ);
}

After:

private static final float FRUSTUM_PAD = 32.0F;

@Override
public boolean testAab(float minX, float minY, float minZ,
                       float maxX, float maxY, float maxZ) {
    return this.frustum.testAab(
        minX - FRUSTUM_PAD, minY - FRUSTUM_PAD, minZ - FRUSTUM_PAD,
        maxX + FRUSTUM_PAD, maxY + FRUSTUM_PAD, maxZ + FRUSTUM_PAD
    );
}

Compiled with javac -source 1.8 -target 1.8, repacked with jar cfM so the original META-INF/MANIFEST.MF (FMLCorePlugin, TweakClass, FMLAT, etc.) is preserved.

Result

• Edge-chunk pop-in is completely eliminated even on hard 180° camera whips.
• FPS impact: within noise (~5% in open biomes at render distance 16); no measurable regression in dense terrain.
• Same modpack, same hardware, same configs as the original report — only the patched class differs.
• B:TerrainRendering=true again, all other terrain config options back to defaults.

Suggested upstream change

1. Land the AABB-expansion fix in Celeritas (SimpleFrustum), not Beddium — it benefits every downstream consumer.
2. Consider exposing FRUSTUM_PAD as a config option (default 16–32f), or scaling it with render distance / camera angular velocity.
3. Alternative design worth considering: double-buffer the visibility set so sections that were visible in frame N stay visible through frame N+1, avoiding the need for spatial padding entirely.

Notes

• The patch only affects chunk-section culling. Entity / TileEntity pop-in (if observed) would need a separate change in Beddium's own FrustrumMixin (vanilla net.minecraft.client.renderer.culling.Frustrum). Not observed in this test.
• MEGAChunks=0 in this test, so the alternative OcclusionCullerMixin traversal path was not exercised.